In general, spiral ducts are used in air handing units, pipelines for transferring particles and so on.
Normally, an apparatus for manufacturing the spiral ducts has a plurality of pressing rollers provided therein. While a thin metal plate member wound around a reel passes through the plurality of pressing rollers, both edges of the metal plate member are bent in the reverse direction.
As the metal plate member is pressed by the pressing rollers after both of the bent edges thereof are coupled to each other, the metal plate member is formed into a cylindrical shape. In this case, the metal plate member is guided while being supported by a plurality of guide rods installed in a circumferential direction on the cylinder.
As the metal plate member is connected continuously, a spiral duct is formed. When the spiral duct is formed to have a proper length, the spiral duct is cut by a circular cutter.
Such a representative spiral duct manufacturing apparatus is disclosed in Korean Unexamined Utility Model No. 1999-5329 (hereinafter, referred to as ‘the related art’). Referring to FIGS. 1A to 1F, the construction of the spiral duct manufacturing apparatus will be described.
As shown in the drawings, the spiral duct manufacturing apparatus according to the related art carries a metal plate member 18, supplied from a reel stand 19, through a plurality of bending rollers 21 arranged in plural lines so as to bend both ends of the metal plate member 18. Then, both ends of the metal plate member 18 are pressed by pressing rollers 31 so as to form a cylindrical duct, and the duct is cut by a circular saw blade 42. At the exit side of the bending rollers 21, a transfer unit 2 including a pair of driving rollers 22 is installed on a first table 11.
The driving rollers 22 are composed of a lower driving roller 24 which is connected to a cylinder 25 so as to operate in the vertical direction and an upper driving roller 23 which is disposed above the lower driving roller 24 and receives power from a driving motor 26.
On a second table 12, a forming unit 3 is installed, including a bolt 32 which adjusts a pressing force for coupling the bent portions 18a and 18b of the metal plate member 18 supplied from the transfer unit 2, a pair of pressing rollers 31 to which the distal end of a lever 33 having the bolt 32 fastened thereto is coupled, and a circular frame 34 which guides a duct which is formed in a cylinder shape while passing through the pressing rollers 31.
The circular frame 34 has a spiral guide groove 35 formed on the inner circumferential surface thereof, the spiral guide groove 35 serving to guide the duct.
Under the forming unit 3, a cutting unit 4 is installed on the second table 12. The cutting unit 4 includes an operating plate 41 which slides on the second table 12, a bracket 46 which is installed on the distal end of the operating plate 41 so as to connect the circular saw blade 42, a motor 43 for rotating the circular saw blade 42, and a cylinder 44 which adjusts the height of the circular saw blade 42.
On the second table 12, a cylinder 47 for moving and returning the cutting unit 4 is installed. The first and second tables 11 and 12 are connected through a guide plate 5.
In the spiral duct manufacturing apparatus according to the related art, manufacturing the circular frame 34 having the guide groove 35 consumes a great deal of operation time. Further, since the spiral duct manufacturing apparatus includes the plurality of motors 26 and 43 and the cylinders 44 and 47, a manufacturing cost increases.
Further, the spiral duct manufacturing apparatus can manufacture a spiral duct formed in a straight line, but cannot manufacture an elbow-shaped spiral duct.